Discrete Frequency Noise Reduction of the Cross-Flow Fan of the Split Type Room Air-Conditioners Using the Skewed Stabilizers.

Abstract

The cross-flow fan system of the split type room air-conditioners often generates the discrete noise component that is called the Blade Passing Frequency tone. It has been known that the BPF tone is generated due to the fluctuating pressure field of the aerodynamic interaction between the rotating fan blades and the stationary stabilizer (or cut-off). Several methods have been invented to reduce this BPF noise. One of the promising schemes is to skew the stabilizer with respect to the fan blade span, which shifts the phase of the pressure fluctuations along the fan span. In this study some experiments have been carried out to investigate influences on the performance and the noise characteristics of the various skew shapes of the stabilizer with the experimental rig which simulates the indoor unit of the split type room air-conditioners. Also a guide is proposed to develop an optimal skew shape of the stabilizer, which dose not significantly impede the aerodynamic performance and has a better noise characteristics.